![]() For instance - it will work with MacBook5,1 and will not work with MacBook1,1Īlternatively you can leave any model but change the platform configuration file to enable SpeedStep. A correct Mac model needs to be chosen.A correct CPU section must be present in ACPI (SSDT).HPET needs to be fixed, which can be done with mask 0x0010.Why is this needed at all? The purpose of it is to allow the CPU to work with its lowest frequency and voltage when it is idling (to reduce power and heat) and to increase both under load again.ĮIST can be activated using several options: using a special utility like CoolBookController or GenericCPUPM, or enabling native native SpeedStep where following steps are required: Clover does not fully automate this process, you still need to adjust some things manually. ![]() This topic is more about setting up a hackintosh than about the boot loader, but as Clover performs several steps, they are described separately. The topic is for very old computers like Core2Duo. the maximum frequency for given voltage will change by about 5%, so make sure that you have at least this much margin in either frequency or voltage (10%) or you will have problems later.It is more correct to say power management and CPU frequency control or simply EIST - Enhanced Intel SpeedStep Technology. Reducing voltage is also good, however make sure you have plenty of margin to failure, or you will end-up crashing your system when the temperature changes.Īlso, realize that over a few years, your microprocessor will likely slow down ~5%, i.e. They may run so hot that if you have a leaky one, leakage power dominates on a hot day. Though that may be debatable for a very fast new Intel processor. ![]() Much of the consumed power should be dynamic, proportional to clock frequency. Reducing CPU frequency is the easiest surefire way to reduce power. I hope the cpu test performs a ram bist …. your CPU is not fast enough to keep up with the clock, this can usually be corrected for by reducing clock speedī) getting memory/cache errors, this can mess up your runtime system, also, if your system has crashed before a hardisk “sync” you may lose some data you thought had been saved. Lowering your CPU voltage may have two undesirable concequences,Ī) crashing your CPU due to timing violations, i.e. You won’t lose all the data on your hard drive, as that storage is non-volatile. Notice how the voltages are lower across the board: Based on these results, I created and saved the following new P-state table. Success! I am able to run the minimum voltage all the way up to 1.8 GHz, and for the top speed of 2 GHz, I can drop all the way down to 1.0125v. A quick note on the CPUTest tool: it seems advisable to run two instances (this is a dual core CPU) for at least 10 minutes before declaring stability. The plan is to apply that same voltage to successively higher clock frequencies, until the machine crashes or fails our stress test. The slowest clock speed will already use the lowest possible voltage by default. Our goal is to find the minimum stable voltage for each P-state. In all likelihood, the defaults are overly conservative. Notice how the voltage increases with each frequency step. Upon launching CoolBookController you will see your default P-state table. Now that we have a baseline, it’s time to undervolt. While performing this initial test the exhaust fan hit 6200 RPM fairly quickly, and the CPU eventually stabilized around 180☏. My system did an emergency shutdown 1 hour and 26 minutes later. Start a stopwatch and yank the power plug.Kick off CPUTest (2 instances, unlimited repetitions).Open Energy Saver, Settings for Battery: Set both sleep sliders to “never”.This is totally atypical, but I could not imagine a fair way to reproduce “typical usage”. In the interest of time (and consistency) I decided to measure with the system at 100% load. To start, we should measure current battery life. (For more detailed info, there’s a great article at Nordic Hardware.) I’m going to assume a basic knowledge of undervolting, and merely describe the process and results for my MacBook. You should be prepared to boot your mac into safe mode, in the event that something goes awry. Undervolting cannot damage your CPU, but it can cause your machine to crash. This has no effect whatsoever on performance, but can extend battery life and reduce heat dissipation. ![]() Briefly, undervolting is the process of manipulating a processor’s P-state tables to cause it to run at a lower voltage, while keeping frequency unchanged.
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